This invention relates to a method of producing a noble metal catalyst, and more particularly, to a method of producing a metal on metal oxide catalyst for use in a carbon dioxide laser.
In a closed cycle carbon dioxide laser, a high voltage discharge is used to initiate laser emission. However, this electrical discharge also causes some of the carbon dioxide in the laser to partially dissociate into carbon monoxide and oxygen in the high voltage discharge region. The continual dissociation of carbon monoxide during laser operation causes the concentration of carbon dioxide to decrease and that of carbon monoxide and oxygen to increase. The loss of carbon dioxide coupled with the gain in oxygen causes a rapid loss in laser power. To maintain laser power, it is necessary to recombine the carbon monoxide and oxygen products.
While different catalysts have been used to effect the recombination of carbon monoxide and oxygen, the CO.sub.2 laser demands a catalyst which is very efficient at room temperature. It has been found that noble metal on tin(IV) oxide catalysts supported on an inert substrate are effective under such conditions. There are several known methods of making such catalysts. However, all of these processes include either time consuming extra drying and calcining steps or the use of chloride-containing materials. The use of chloride containing compounds necessitates thorough washing of the catalyst, because chloride is known to poison and deactivate the catalyst. Consequently, a need continues to exist for a simple, chloride-free method of producing a noble metal on metal oxide catalyst for use in a closed-cycle CO.sub.2 laser.
Accordingly, it is an object of this invention to provide a simple method of producing a noble metal on metal oxide catalyst on an inert, high-surface area substrate using chloride-free reagents for use in a CO.sub.2 laser.
A further object of this invention is to provide a one-step method of adding a layer of a metal oxide to an inert support material.
A further object of this invention is to provide a one-step method of adding a layer of a noble metal to metal oxide on an inert support.
A further object of this invention is to provide a method of producing a noble metal on metal oxide catalyst wherein the reagents used and products formed during the reaction are either volatile or decompose to volatile products during drying.
Other objects and advantages of this invention will become apparent hereinafter in the specification which follows.